rio-build

Use when running checks or nix builds in this repo — the fast edit-loop check (clippy/docs/policy, no test execution), the full CI gate, .#coverage, or any single flake target. Keeps build output out of agent context — full log to /tmp/rio-dev/, short report on stdout.

Bump flake inputs in lockstep. rio-build has no reference submodules (rio-build is the ORIGINAL implementation, not a port) — this just wraps `nix flake update` for the inputs that matter.